diff --git a/aegisub/configure.in b/aegisub/configure.in
index 11b8c6545..566db6165 100644
--- a/aegisub/configure.in
+++ b/aegisub/configure.in
@@ -16,12 +16,6 @@ m4_define([aegisub_version_data], [aegisub_version_major.aegisub_version_minor])
 ###################
 # Required packages
 ###################
-m4_define([libavcodec_required_version], [52.27.0])  # (r18642)
-m4_define([libavformat_required_version], [52.32.0]) # (r18642)
-m4_define([libavutil_required_version], [50.3.0])    # (r18642)
-m4_define([libpostproc_required_version], [51.2.0])  # (r18642)
-m4_define([libswscale_required_version], [0.7.1])    # (r18642)
-
 m4_define([lua_auto3_required_version], [5.0])
 m4_define([lua_auto4_required_version], [5.1])
 m4_define([portaudio_required_version], [19])
@@ -102,7 +96,7 @@ if test "$build_darwin" = "yes"; then
   fi
   AC_SUBST(DARWIN_ARCH)
 
-  CXXFLAGS_OSX="-mmacosx-version-min=10.4"
+  CXXFLAGS_OSX="-mmacosx-version-min=10.5"
 
   case "$target_or_host" in
     # 10.4
@@ -217,7 +211,6 @@ AM_PROG_CC_C_O
 define([AC_LIBTOOL_LANG_F77_CONFIG], [:])
 AC_PROG_LIBTOOL
 AC_PROG_INSTALL
-AC_PROG_RANLIB
 PKG_PROG_PKG_CONFIG([pkgconfig_required_version])
 
 
@@ -242,7 +235,7 @@ else
 fi
 
 # This is required in order for the config file to work correctly.
-AC_DEFINE_UNQUOTED([BUILD_SVN_REVISION], [$SVN_REVISION], [SVN Revision number, used for config.dat and verison.cpp])
+AC_DEFINE_UNQUOTED([BUILD_SVN_REVISION], [$SVN_REVISION], [SVN Revision number, used for config.dat and version.cpp])
 
 
 # Release information.
@@ -357,7 +350,7 @@ AC_CHECK_HEADER([wchar.h],,[AC_MSG_FAILURE([aegisub requires wide character supp
 ## OpenGL
 #########
 AX_CHECK_GL
-if test ! "$GL_LIBS"; then
+if test "x$GL_LIBS" = "x"; then
 	AC_MSG_FAILURE([aegisub requires GL support.])
 fi
 AC_SUBST(GL_CFLAGS)
@@ -469,30 +462,40 @@ AC_SUBST(ICONV_CFLAGS)
 #######
 ## ALSA
 #######
-AC_ARG_WITH(alsa, [  --without-alsa          build without ALSA audio provider. (default: auto)], alsa_disabled="(disabled)")
+AC_ARG_WITH(alsa, [  --without-alsa          build without ALSA audio provider. (default: auto)],[],[with_alsa="auto";alsa_disabled="(autodetected)"])
 
 AC_ARG_VAR([ALSA_CFLAGS], [CFLAGS to use for ALSA (default: CPPFLAGS)])
 AC_ARG_VAR([ALSA_LIBS], [LIBS to use for ALSA (default: -lasound -lrt)])
 
-if test -z "$ALSA_LIBS"; then
-  ALSA_LIBS="-lasound -lrt";
-fi
+AS_IF([test "x$with_alsa" != "xno"],[
+  if test -z "$ALSA_LIBS"; then
+    ALSA_LIBS="-lasound -lrt";
+  fi
 
-if test -z "$ALSA_CFLAGS"; then
-  ALSA_CFLAGS="$CPPFLAGS"; # I don't get this. Why CPPFLAGS? I would understand CFLAGS and even CXXFLAGS, but why CPPFLAGS? -Fluff
-fi
+  if test -z "$ALSA_CFLAGS"; then
+    ALSA_CFLAGS="$CPPFLAGS"; # I don't get this. Why CPPFLAGS? I would understand CFLAGS and even CXXFLAGS, but why CPPFLAGS? -Fluff
+  fi
 
-if test "$with_alsa" != "no"; then
   aegisub_save_LIBS="$LDFLAGS"
   LIBS="$ALSA_LIBS"
-  AC_CHECK_LIB([asound], [snd_pcm_open], [ALSA_LIBS="-lasound -lrt"; with_alsa="yes"], [with_alsa="no"])
+  AC_CHECK_LIB([asound], [snd_pcm_open], [
+    ALSA_LIBS="-lasound -lrt"
+    with_alsa="yes"
+  ], [
+    AS_IF([test "x$with_alsa" != "xauto"],[
+      AC_MSG_FAILURE([ALSA was specified as required, but was not detected.])
+    ],[])
+    with_alsa="no"
+  ])
   LIBS="$aegisub_save_LIBS"
-fi
+],[
+  alsa_disabled="(disabled)"
+])
 
-if test "$with_alsa" != "no"; then
+AS_IF([test "x$with_alsa" = "xyes"],[
   AC_DEFINE(WITH_ALSA, 1, [Enable ALSA Support])
   found_audio_player="yes"
-fi
+],[])
 
 AM_CONDITIONAL([HAVE_ALSA], [test "$with_alsa" != "no"])
 AC_SUBST(ALSA_LIBS)
@@ -503,30 +506,25 @@ AC_SUBST(ALSA_LIBS)
 ############
 
 AC_ARG_WITH(portaudio,[  --without-portaudio     build without PortAudio v19 audio provider.
-                          (default: auto)], portaudio_disabled="(disabled)")
-if test "$with_portaudio" != "no"; then
-  PKG_CHECK_MODULES(PORTAUDIO, portaudio-2.0 >= portaudio_required_version, [with_portaudio="yes"], [with_portaudio="no"])
-fi
+                          (default: auto)],[],[with_portaudio="auto";portaudio_disabled="(autodetected)"])
 
-if test "$with_portaudio" != "no"; then
-  AC_AGI_COMPILE([PortAudio], [portaudio], [$PORTAUDIO_CFLAGS], [$PORTAUDIO_LIBS],[
-#include <portaudio.h>
-int main(void) {
-  PaError err = Pa_Initialize();
-  if (err != paNoError) return 1;
-  return 0;
-} ])
-fi
+AS_IF([test "x$with_portaudio" != "xno"],[
+  PKG_CHECK_MODULES(PORTAUDIO, portaudio-2.0 >= portaudio_required_version, [
+    with_portaudio="yes"
+  ], [
+    AS_IF([test "x$with_portaudio" != "xauto"],[
+      AC_MSG_FAILURE([PortAudio was specified as required, but was not detected.])
+    ],[])
+    with_portaudio="no"
+  ])
+],[
+  portaudio_disabled="(disabled)"
+])
 
-if test "$agi_cv_with_portaudio" = "no" && test "$with_portaudio" = "yes"; then
-  AC_MSG_WARN([PortAudio detected, but it doesn't work...])
-  with_portaudio="no"
-fi
-
-if test "$agi_cv_with_portaudio" = "yes" && test "$with_portaudio" = "yes"; then
+AS_IF([test "$with_portaudio" = "yes"],[
   AC_DEFINE(WITH_PORTAUDIO, 1, [Enable PortAudio v19 support])
   found_audio_player="yes"
-fi
+],[])
 
 AM_CONDITIONAL([HAVE_PORTAUDIO], [test "$with_portaudio" != "no"])
 
@@ -536,30 +534,25 @@ AM_CONDITIONAL([HAVE_PORTAUDIO], [test "$with_portaudio" != "no"])
 #############
 
 AC_ARG_WITH(pulseaudio,[  --with-pulseaudio       build with PulseAudio audio provider.
-                          (default: auto)], [pulseaudio_disabled="(disabled)"])
-if test "$with_pulseaudio" != "no"; then
-  PKG_CHECK_MODULES(LIBPULSE, libpulse >= pulseaudio_required_version, [with_pulseaudio="yes"], [with_pulseaudio="no"])
-fi
+                          (default: auto)],[],[with_pulseaudio="auto";pulseaudio_disabled="(autodetected)"])
 
-if test "$with_pulseaudio" != "no"; then
-  AC_AGI_COMPILE([PulseAudio], [pulseaudio], [$LIBPULSE_CFLAGS], [$LIBPULSE_LIBS],[
-#include <pulse/pulseaudio.h>
-int main(void) {
-pa_threaded_mainloop *mainloop = pa_threaded_mainloop_new();
-if (!mainloop) return 1;
-return 0;
-} ])
-fi
+AS_IF([test "x$with_pulseaudio" != "xno"],[
+  PKG_CHECK_MODULES(LIBPULSE, libpulse >= pulseaudio_required_version, [
+    with_pulseaudio="yes"
+  ], [
+    AS_IF([test "x$with_pulseaudio" != "xauto"],[
+      AC_MSG_FAILURE([PulseAudio was specified as required, but was not detected.])
+    ],[])
+    with_pulseaudio="no"
+  ])
+],[
+  pulseaudio_disabled="(disabled)"
+])
 
-if test "$agi_cv_with_pulseaudio" = "no" && test "$with_pulseaudio" = "yes"; then
-  AC_MSG_WARN([PulseAudio detected, but it doesn't work...])
-  with_pulseaudio="no"
-fi
-
-if test "$agi_cv_with_pulseaudio" = "yes" && test "$with_pulseaudio" = "yes"; then
+AS_IF([test "x$with_pulseaudio" = "xyes"],[
   AC_DEFINE(WITH_PULSEAUDIO, 1, [Enable PulseAudio support])
   found_audio_player="yes"
-fi
+],[])
 
 AM_CONDITIONAL([HAVE_PULSEAUDIO], [test "$with_pulseaudio" != "no"])
 
@@ -568,38 +561,25 @@ AM_CONDITIONAL([HAVE_PULSEAUDIO], [test "$with_pulseaudio" != "no"])
 ## OpenAL
 #########
 AC_ARG_WITH(openal,[  --without-openal        build without OpenAL audio provider.
-                          (default: auto)], openal_disabled="(disabled)")
-if test "$with_openal" != "no"; then
-  PKG_CHECK_MODULES(OPENAL, openal >= 0.0.8, [with_openal=yes], [with_openal=no])
-fi
+                          (default: auto)],[],[with_openal="auto";openal_disabled="(autodetected)"])
 
-if test "$with_openal" != "no"; then
-  AC_AGI_COMPILE([OpenAL], [openal], [$OPENAL_CFLAGS], [$OPENAL_LIBS],[
-#if defined(__APPLE__)
-#include <OpenAL/AL.h>
-#include <OpenAL/ALC.h>
-#else
-#include <AL/al.h>
-#include <AL/alc.h>
-#endif
-int main(void) {
-  ALCdevice *device = alcOpenDevice(0);
-  if (!device) return 1;
-  ALCcontext *context = alcCreateContext(device, 0);
-  if (!context) return 1;
-  return 0;
-} ])
-fi
+AS_IF([test "x$with_openal" != "xno"],[
+  PKG_CHECK_MODULES(OPENAL, openal >= 0.0.8, [
+    with_openal=yes
+  ], [
+    AS_IF([test "x$with_openal" != "xauto"],[
+      AC_MSG_FAILURE([OpenAL was specified as required, but was not detected.])
+    ],[])
+    with_openal=no
+  ])
+],[
+  openal_disabled="(disabled)"
+])
 
-if test "$agi_cv_with_openal" = "no" && test "$with_openal" = "yes"; then
-  AC_MSG_WARN([OpenAL detected, but it doesn't work...])
-  with_openal="no"
-fi
-
-if test "$agi_cv_with_openal" = "yes" && test "$with_openal" = "yes"; then
-  found_audio_player="yes"
+AS_IF([test "x$with_openal" = "xyes"],[
   AC_DEFINE(WITH_OPENAL, 1, [Enable OpenAL support])
-fi
+  found_audio_player="yes"
+],[])
 
 AM_CONDITIONAL([HAVE_OPENAL], [test "$with_openal" != "no"])
 
@@ -608,20 +588,29 @@ AM_CONDITIONAL([HAVE_OPENAL], [test "$with_openal" != "no"])
 ## OSS
 ######
 AC_ARG_WITH(oss,[  --without-oss           build without OSS audio provider.
-                          (default: auto)], oss_disabled="(disabled)")
-if test "$with_oss" != "no"; then
-  if test -f "/etc/oss.conf"; then
+                          (default: auto)],[],[with_oss="auto";oss_disabled="(autodetected)"])
+
+AS_IF([test "x$with_oss" != "xno"],[
+  AS_IF([test -f "/etc/oss.conf"],[
     . /etc/oss.conf
     CPPFLAGS="$CPPFLAGS -I${OSSLIBDIR}/include/sys"
-  fi
-  AC_CHECK_HEADERS([soundcard.h sys/soundcard.h], [with_oss="yes"], [with_oss="no"])
-  # XXX: maybe check if OSS works
-fi
+  ],[])
+  AC_CHECK_HEADERS([soundcard.h sys/soundcard.h], [
+    with_oss="yes"
+  ], [
+    AS_IF([test "x$with_oss" != "xauto"],[
+      AC_MSG_FAILURE([OSS support was specified as required, but was not detected.])
+    ],[])
+    with_oss="no"
+  ])
+],[
+  oss_disabled="(disabled)"
+])
 
-if test "$with_oss" != "no"; then
-  found_audio_player="yes"
+AS_IF([test "x$with_oss" != "xno"],[
   AC_DEFINE(WITH_OSS, 1, [Enable OSS support])
-fi
+  found_audio_player="yes"
+],[])
 
 AM_CONDITIONAL([HAVE_OSS], [test "$with_oss" != "no"])
 
@@ -631,18 +620,29 @@ AM_CONDITIONAL([HAVE_OSS], [test "$with_oss" != "no"])
 #########################
 
 
-AC_ARG_WITH(provider-ffms,[  --without-ffms          disable FFmpegSource support (default: auto)],ffms_provider_disabled="(disabled)")
+AC_ARG_WITH(ffms,[  --without-ffms          disable FFmpegSource support (default: auto)],[],[with_ffms="auto";ffms_provider_disabled="(autodetected)"])
 
-if test "$with_provider_ffms" != "no"; then
-  PKG_CHECK_MODULES(FFMS, ffms2 >= ffms_required_version, [with_provider_ffms="yes"], [with_provider_ffms="no"])
-fi
+AS_IF([test "x$with_ffms" != "xno"],[
+  PKG_CHECK_MODULES(FFMS, ffms2 >= ffms_required_version, [
+    with_ffms="yes"
+  ], [
+    AS_IF([test "x$with_ffms" != "xauto"],[
+      AC_MSG_FAILURE([FFmpegSource was specified as required, but was not detected.])
+    ],[])
+    with_ffms="no"
+  ])
+],[
+  ffms_provider_disabled="(disabled)"
+])
 
-if test "$with_provider_ffms" = "yes"; then
+AS_IF([test "x$with_ffms" = "xyes"],[
   AC_DEFINE(WITH_FFMPEGSOURCE, 1, [Enable FFmpegSource2 video provider])
   found_video_provider="yes"
-fi
+],[
+  with_ffms="no"
+])
 
-AM_CONDITIONAL([HAVE_PROVIDER_FFMPEGSOURCE], [test "$with_provider_ffms" = "yes"])
+AM_CONDITIONAL([HAVE_PROVIDER_FFMPEGSOURCE], [test "$with_ffms" = "yes"])
 
 AC_SUBST(FFMS_CFLAGS)
 
@@ -651,17 +651,26 @@ AC_SUBST(FFMS_CFLAGS)
 # Subtitle Provider
 ###################
 
-AC_ARG_ENABLE(libass, [  --without-libass        disable libass support (default=enabled)],libass_disabled="(disabled)")
+AC_ARG_WITH(libass, [  --without-libass        disable libass support (default=auto)],[],[with_libass="auto";libass_disabled="(autodetected)"])
 
-if test "$enable_libass" != "no"; then
-  PKG_CHECK_MODULES(LIBASS, libass >= libass_required_version, [with_libass="yes"], [with_libass="no"])
-fi
+AS_IF([test "x$with_libass" != "xno"],[
+  PKG_CHECK_MODULES(LIBASS, libass >= libass_required_version, [
+    with_libass="yes"
+  ], [
+    AS_IF([test "x$with_libass" != "xauto"],[
+      AC_MSG_FAILURE([libass was specified as required, but was not detected.])
+    ],[])
+    with_libass="no"
+  ])
+],[
+  libass_disabled="(disabled)"
+])
 
-if test "$with_libass" = "yes" || test "$enable_libass" != "no"; then
+AS_IF([test "x$with_libass" = "xyes"],[
   AC_DEFINE(WITH_LIBASS, 1, [Enable libass Subtitle Provider])
-else
+],[
   with_libass="no"
-fi
+])
 
 AM_CONDITIONAL([WITH_LIBASS], [test "$with_libass" = "yes"])
 AC_SUBST(LIBASS_LIBS)
@@ -672,28 +681,24 @@ AC_SUBST(LIBASS_CFLAGS)
 ###########
 ## Hunspell
 ###########
-AC_ARG_WITH(hunspell, [  --without-hunspell      build without hunspell support (default: auto)], hunspell_disabled="(disabled)")
+AC_ARG_WITH(hunspell, [  --without-hunspell      build without hunspell support (default: auto)],[],[with_hunspell="auto";hunspell_disabled="(autodetected)"])
 
-if test "$with_hunspell" != "no"; then
-  PKG_CHECK_MODULES(HUNSPELL, hunspell >= 1.2.0, [with_hunspell="yes"], [with_hunspell="no"])
-  AC_AGI_COMPILE([Hunspell], [hunspell], [$HUNSPELL_CFLAGS], [$HUNSPELL_LIBS],[
-#include <hunspell.hxx>
-int main(void) {
-  Hunspell *hunspell;
-  hunspell = new Hunspell(".", ".");
-  if (!hunspell) return 1;
-  return 0;
-}  ])
-fi
+AS_IF([test "x$with_hunspell" != "xno"],[
+  PKG_CHECK_MODULES(HUNSPELL, hunspell >= 1.2.0, [
+    with_hunspell="yes"
+  ], [
+    AS_IF([test "x$with_hunspell" != "xauto"],[
+      AC_MSG_FAILURE([hunspell was specified as required, but was not detected.])
+    ],[])
+    with_hunspell="no"
+  ])
+],[
+  hunspell_disabled="(disabled)"
+])
 
-if test "$agi_cv_with_hunspell" = "no" && test "$with_hunspell" = "yes"; then
-  AC_MSG_WARN([Hunspell detected, but it doesn't work...])
-  with_hunspell="no"
-fi
-
-if test "$agi_cv_with_hunspell" = "yes" && test "$with_hunspell" = "yes"; then
+AS_IF([test "x$with_hunspell" = "xyes"],[
   AC_DEFINE(WITH_HUNSPELL, 1, [Enable Hunspell support.])
-fi
+],[])
 
 AM_CONDITIONAL([HAVE_HUNSPELL], [test "$with_hunspell" != "no"])
 
@@ -702,12 +707,13 @@ AM_CONDITIONAL([HAVE_HUNSPELL], [test "$with_hunspell" != "no"])
 ######################
 ## universalchardetect
 ######################
-AC_ARG_ENABLE(univchardet, [  --disable-univchardet   disble universalchardet support.], univchardet_disabled="(disabled)")
+AC_ARG_ENABLE(univchardet, [  --disable-univchardet   disble universalchardet support.],[],[univchardet_disabled="(default)"])
 if test "$enable_univchardet" != "no"; then
   with_univchardet="yes"
   AC_DEFINE(WITH_UNIVCHARDET, 1, [Enable universalchardet support])
 else
   with_univchardet="no"
+  univchardet_disabled="(disabled)"
 fi
 AM_CONDITIONAL([HAVE_UNIVCHARDET], [test "$with_univchardet" != "no"])
 
@@ -723,23 +729,23 @@ AM_CONDITIONAL([HAVE_UNIVCHARDET], [test "$with_univchardet" != "no"])
 ############
 
 AC_ARG_WITH(lua,
-[  --without-lua           build without lua 5.1 (auto4)], [lua51_disabled="(disabled)"])
+[  --without-lua           build without lua 5.1 (auto4)],[],[with_lua="auto";lua51_disabled="(autodetected)"])
 
 AC_ARG_VAR([LUA_CFLAGS], [CFLAGS to use for LUA 5.1 (default: autodetect)])
 AC_ARG_VAR([LUA_LDFLAGS], [LDFLAGS to use for LUA 5.1 (default: autodetect)])
 AC_ARG_VAR([LUA_LIBDIR], [Location of LUA 5.1 library. (default: none)])
 
-if test -z "$LUA_CFLAGS"; then
-  AGI_FIND_HEADER([LUA], [lua.hpp], [/usr/include/lua5.1 /usr/include/lua51 /usr/local/include/lua51 /usr/local/include/lua5.1 /usr/include /usr/local/include])
-fi
+AS_IF([test "x$with_lua" != "xno"],[
+  if test -z "$LUA_CFLAGS"; then
+    AGI_FIND_HEADER([LUA], [lua.hpp], [/usr/include/lua5.1 /usr/include/lua51 /usr/local/include/lua51 /usr/local/include/lua5.1 /usr/include /usr/local/include])
+  fi
 
-if test -z "$LUA_LDFLAGS"; then
-  AGI_FIND_LIB([LUA], [lua51 lua-5.1 lua5.1 lua], [$LUA_LIBDIR])
-fi
+  if test -z "$LUA_LDFLAGS"; then
+    AGI_FIND_LIB([LUA], [lua51 lua-5.1 lua5.1 lua], [$LUA_LIBDIR])
+  fi
 
-aegisub_save_LIBS="$LIBS"
-LIBS="$LUA_LDFLAGS"
-if test "$with_lua" != no; then
+  aegisub_save_LIBS="$LIBS"
+  LIBS="$LUA_LDFLAGS"
   AC_AGI_COMPILE([Lua 5.1 (auto4)], [lua], [$LUA_CFLAGS], [$LUA_LDFLAGS],[
 #include <lua.hpp>
 
@@ -750,16 +756,21 @@ int main () {
   lua_close(L);
   return !res;
 }])
-fi
-LIBS="$aegisub_save_LIBS"
+  LIBS="$aegisub_save_LIBS"
 
-if test "$agi_cv_with_lua" = "yes"; then
-  with_auto4="yes"
-  with_automation="yes"
-  AC_DEFINE(WITH_AUTO4_LUA, 1, [Enable Automation (auto4), requires lua])
-else
-  with_auto4="no"
-fi
+  AS_IF([test "x$agi_cv_with_lua" = "xyes"],[
+    with_auto4="yes"
+    with_automation="yes"
+    AC_DEFINE(WITH_AUTO4_LUA, 1, [Enable Automation (auto4), requires Lua 5.1])
+  ],[
+    AS_IF([test "x$with_lua" != "xauto"],[
+      AC_MSG_FAILURE([Lua 5.1 support was specified as required, but was not detected.])
+    ],[])
+    with_auto4="no"
+  ])
+],[
+  lua51_disabled="(disabled)"
+])
 
 AM_CONDITIONAL([HAVE_AUTO4_LUA], [test "$with_auto4" != "no"])
 AC_SUBST(LUA_CFLAGS)
@@ -771,22 +782,22 @@ AC_SUBST(LUA_LDFLAGS)
 ##################
 
 AC_ARG_WITH(lua50,
-[  --without-lua50         build without lua 5.0 (auto3)], [lua50_disabled="(disabled)"])
+[  --without-lua50         build without lua 5.0 (auto3)],[],[with_lua50="auto";lua50_disabled="(autodetected)"])
 
 AC_ARG_VAR([LUA50_CFLAGS], [CFLAGS to use for LUA 5.1 (default: autodetect)])
 AC_ARG_VAR([LUA50_LDFLAGS], [LDFLAGS to use for LUA 5.1 (default: autodetect)])
 AC_ARG_VAR([LUA50_LIBDIR], [Location of LUA 5.1 library. (default: none)])
 
-if test -z "$LUA50_CFLAGS"; then
-  AGI_FIND_HEADER([LUA50], [lua.h], [/usr/include/lua5.0 /usr/include/lua50 /usr/local/include/lua50 /usr/local/include/lua5.0 /usr/include /usr/local/include])
-fi
+AS_IF([test "x$with_lua50" != "xno"],[
+  if test -z "$LUA50_CFLAGS"; then
+    AGI_FIND_HEADER([LUA50], [lua.h], [/usr/include/lua5.0 /usr/include/lua50 /usr/local/include/lua50 /usr/local/include/lua5.0 /usr/include /usr/local/include])
+  fi
 
-if test -z "$LUA50_LDFLAGS"; then
-  AGI_FIND_LIB([LUA50], [lua50 lua-5.0 lua5.0 lua], [$LUA50_LIBDIR])
-  AGI_FIND_LIB([LUALIB50], [lualib50 lualib-5.0 lualib5.0 lualib], [$LUA50_LIBDIR], [$LUA50_LDFLAGS])
-fi
+  if test -z "$LUA50_LDFLAGS"; then
+    AGI_FIND_LIB([LUA50], [lua50 lua-5.0 lua5.0 lua], [$LUA50_LIBDIR])
+    AGI_FIND_LIB([LUALIB50], [lualib50 lualib-5.0 lualib5.0 lualib], [$LUA50_LIBDIR], [$LUA50_LDFLAGS])
+  fi
 
-if test "$with_lua50" != no; then
   AC_AGI_COMPILE([Lua 5.0 (auto3)], [lua50], [$LUA50_CFLAGS], [$LUA50_LDFLAGS $LUALIB50_LDFLAGS],[
 extern "C" {
 #include "lua.h"
@@ -801,15 +812,20 @@ int main() {
   luaL_newmetatable(L, "test");
   lua_close(L);
 }])
-fi
 
-if test "$agi_cv_with_lua50" = "yes"; then
-  with_auto3="yes"
-  with_automation="yes"
-  AC_DEFINE(WITH_AUTO3, 1, [Enable Automation (auto3, DEPRECIATED!), requires lua 5.0])
-else
-  with_auto3="no"
-fi
+  AS_IF([test "x$agi_cv_with_lua50" = "xyes"],[
+    with_auto3="yes"
+    with_automation="yes"
+    AC_DEFINE(WITH_AUTO3, 1, [Enable Automation (auto3, DEPRECIATED!), requires lua 5.0])
+  ],[
+    AS_IF([test "x$with_lua50" != "xauto"],[
+      AC_MSG_FAILURE([Lua 5.0 support was specified as required, but was not detected.])
+    ],[])
+    with_auto3="no"
+  ])
+],[
+  lua50_disabled="(disabled)"
+])
 
 AM_CONDITIONAL([HAVE_AUTO3_LUA], [test "$with_auto3" != "no"])
 AC_SUBST(LUA50_CFLAGS)
@@ -821,7 +837,7 @@ AC_SUBST(LUALIB50_LDFLAGS)
 #############
 ## Auto4 PERL
 #############
-AC_ARG_WITH(perl, [  --with-perl             build with PERL Automation. (default: no)], perl_disabled="(disabled)")
+AC_ARG_WITH(perl, [  --with-perl             build with PERL Automation. (default: no)],[],[with_perl="auto";perl_disabled="(default)"])
 AC_ARG_WITH(perl-bin, [  --with-perl-bin=PATH    location of PERL binary. (default: $PATH)], [WITH_PERL_BIN="$withval"])
 
 AC_ARG_VAR([PERL_CFLAGS], [CFLAGS to use for Perl (default: -MExtUtils::Embed -eccflags -eperl_inc)])
@@ -864,11 +880,12 @@ int main(int argc, char **argv, char **env) {
 }])
     fi
   fi
+elif test "x$with_perl" = "xno"; then
+  perl_disabled="(disabled)"
 fi
 
 if test "$agi_cv_with_perl" = "no" && test "$with_cv_perl" = "yes"; then
-  AC_MSG_WARN([Perl detected, but it doesn't work...])
-  with_cv_perl="no"
+  AC_MSG_FAILURE([Perl detected, but it doesn't work...])
 fi
 
 if test "$agi_cv_with_perl" = "yes" && test "$with_cv_perl" = "yes"; then
@@ -878,7 +895,7 @@ else
   with_cv_perl="no"
 fi
 
-AM_CONDITIONAL([HAVE_AUTO4_PERL], [test "$with_cv_perl" != "no"])
+AM_CONDITIONAL([HAVE_AUTO4_PERL], [test "$with_cv_perl" = "yes"])
 AC_SUBST(PERL_CFLAGS)
 AC_SUBST(PERL_LDFLAGS)
 
@@ -893,7 +910,7 @@ fi
 #############
 ## Auto4 Ruby
 #############
-AC_ARG_WITH(ruby, [  --with-ruby             build with Ruby Automation. (default: no)], ruby_disabled="(disabled)")
+AC_ARG_WITH(ruby, [  --with-ruby             build with Ruby Automation. (default: no)],[],[with_ruby="auto";ruby_disabled="(default)"])
 AC_ARG_WITH(ruby-bin, [  --with-ruby-bin=PATH    location of RUBY binary. (default: $PATH)], [WITH_RUBY_BIN="$withval"])
 
 AC_ARG_VAR([RUBY_CFLAGS], [CFLAGS to use for Ruby (default: Config::CONFIG archdir + CFLAGS)])
@@ -936,10 +953,12 @@ int main(void) {
 }])
     fi
   fi
+elif test "x$with_ruby" = "xno"; then
+  ruby_disabled="(disabled)"
 fi
 
 if test "$agi_cv_with_ruby" = "no" && test "$with_cv_ruby" = "yes"; then
-  AC_MSG_WARN([Ruby detected, but it doesn't work...])
+  AC_MSG_FAILURE([Ruby detected, but it doesn't work...])
   with_cv_ruby="no"
 fi
 
@@ -1013,8 +1032,9 @@ fi
 ############################
 
 AC_MSG_CHECKING([whether to use precompiled headers])
-AC_ARG_ENABLE(gcc-prec, [  --enable-gcc-prec       enable GCC precompiled headers (default=no)])
-if test "$enable_gcc_prec" = "yes"; then
+AC_ARG_ENABLE(gcc-prec, [  --enable-gcc-prec       enable GCC precompiled headers (default=auto)],[],[enable_gcc_prec="auto"])
+if test "x$enable_gcc_prec" != "no"; then
+  enable_gcc_prec="yes"
   AC_MSG_RESULT([yes])
 else
   AC_MSG_RESULT([no])
@@ -1196,7 +1216,7 @@ AC_ARG_WITH(player-audio, [  --with-player-audio=(alsa|openal|portaudio|pulseaud
 if ! test -z "$with_provider_video"; then
     default_provider_video="$with_provider_video"
 else
-  if test "$with_provider_ffms" = "yes"; then
+  if test "$with_ffms" = "yes"; then
     default_provider_video="ffmpegsource"
   fi
 fi
@@ -1206,7 +1226,7 @@ AC_DEFINE_UNQUOTED([DEFAULT_PROVIDER_VIDEO], ["$default_provider_video"], [Defau
 if ! test -z "$with_provider_audio"; then
     default_provider_audio="$with_provider_audio"
 else
-  if test "$with_provider_ffms" = "yes"; then
+  if test "$with_ffms" = "yes"; then
     default_provider_audio="ffmpegsource"
   fi
 fi
@@ -1353,12 +1373,12 @@ Audio Players
   PulseAudio:            $with_pulseaudio $pulseaudio_disabled
 
 A/V Providers
-  FFmpegSource:          $with_provider_ffms $ffms_provider_disabled
+  FFmpegSource:          $with_ffms $ffms_provider_disabled
 
 Subtitle Providers:
   libASS                 $with_libass $libass_disabled $libass_default
 
 Misc Packages
-  Hunspell:              $with_hunspell $with_hunspell_version $hunspell_disabled
+  Hunspell:              $with_hunspell $hunspell_disabled
   universalchardet:      $with_univchardet $univchardet_disabled
 ]);